tmilford34

I have heard of ghosts in the machine but this ish is rediculous. This weekend i replaced the CPS and CTS in my jeep and it ran great, still had the really long start but still ran great. I drove today for about 2 hours on the road and it did fine all day until i got about 5 miles from my house. It started lagging bad as if the catalytic converter was bad but mine doesnt have a cat on it. It would barely accelerate until i was almost completely off of the gas. it would not kick down until the pedal was to the floor and even then the kick down gear was not very effective. still idling fine at lights and stops. i get to the house put it in park and try to rev the engine and i get a hesitation and 2-300 rpm drop before it revs up, after i let off of the pedal i get a small backfire. within the last 2k miles i have replaced the CPS, CTS, TPS, MAP, IAC, Fuel and Air filters among other things but these seem to be the only ones applicable to the situation. Any help is much appreciated, Thanks.

CodeXJ

I'm only asking because you didn't mention them, but have you checked the plugs, wires, cap and rotor to make sure they are OK?

What do your plugs look like (and don't say, "Like a spark plug!" )?

You may want to get a fuel pressure tester, the kind that hooks to the fuel rail, and see what it's doing. I think you can rent them from Autozone.

tmilford34

I knew i forgot something, yeah i replaced all that too. have not had a pressure test done though

tmilford34

plugs have less than 1k on them and when i pulled the old ones they had no signs of detonation or any other issues

tmilford34

anybody else got any ideas?

CodeXJ

Don't know what year you have, but maybe test the ignition coil?

Also, have you done a compression test yet? I don't think that'll be your issue, since you said it ran fine for a bit, then went wierd again. But it can't hurt to do and may give us some ideas.

Could be a clogged up fuel system or carbon, I suppose. Try Seafoaming it. Er... as a word of warning, don't have open windows and don't do it in a garage.

tmilford34

its a 1990 with 135,000 on the clock. Ignition coil is a good idea, that is probably going to be my next thing to try. i really have a feeling that the problem is in the ignition system, just looking for some reaffirmation. It currently has seafoam in the gastank and i used about a quarter of the can through the throttle body and surprisingly not much smoke came out...

Willys55

Oxygen Sensor will also cause these symptons.

tmilford34

eventhough there is no CEL on?

Vibraslapp

I'm in the same boat exactly on a 93 XJ. Doing a preasure test tamarrow on the fuel. I replaced all the same things and she is still pissed off. Please keep your thread going and i'll tell you what i find out as well.

trans_am7935

x2 on the fuel pressure test. sounds like your fuel pump is going out. hesitation then backfire, i had the same issue 3 years ago. replace the fuel filter first, could be the culprit and it is cheaper.

4jeepers

Have an exorcism done! It worked on mine! LOL

tmilford34

LOL Know a good priest??

tmilford34

Good idea, i need to do that anyways becuase my check valve has completely gone out, even 2 minutes after i shut it off it doesnt hold enough pressure to start before probably 6 seconds of turning over....

Rock Toy

This sounds like what happened to one of my old cars, it started after a fuel filter was changed. I guess the gunk ( tech term ) broke loose and started plugging the fuel lines, which starved the EFI system and made it so it could only do about 35 mph. I did a fuel pressure check and found problem and replaced the filter again after flushing the tank, no more problems.